Krzysztof Skowron

The Assessment of Proteus mirabilis Susceptibility to Ceftazidime and Ciprofloxacin and the Impact of These Antibiotics at Subinhibitory Concentrations on Proteus mirabilis Biofilms

Rods of the Proteus genus are commonly isolated from patients, especially from the urinary tracts of the catheterised patients. The infections associated with biomaterials are crucial therapeutic obstacles, due to the bactericidal resistance of the biofilm. The aim of this study was to assess the susceptibility of P. mirabilis planktonic forms to ciprofloxacin and ceftazidime, the ability to form biofilm, and the impact of chosen sub-MIC concentrations of these antibiotics on biofilm at different stages of its formation. The research included 50 P. mirabilis strains isolated from wounds and the urinary tracts from patients of the University Hospital No. 1 in Bydgoszcz. The assessment of susceptibility to ciprofloxacin and ceftazidime was conducted using micromethods. The impact of sub-MIC concentrations of the chosen antibiotics on the biofilm was measured using the TTC method. The resistance to ciprofloxacin was confirmed for 20 strains (40.0%) while to ceftazidime for 32 (64.0%) of the tested P. mirabilis strains. All of the tested strains formed biofilm: 24.0% weakly, 26.0% moderately, and 50.0% strongly. It was determined that ciprofloxacin and ceftazidime caused eradication of the biofilm. Moreover, the connection between origin of the strains, biofilm maturity level, and resistance to antibiotics was proved.

UV-C Radiation as a Factor Reducing Microbiological Contamination of Fish Meal

Fish meals, added to feeds as a source of protein, may contain pathogenic bacteria. Therefore, effective methods for their sanitizing, such as UV-C radiation, are needed to minimize the epidemiological risk. The objective of this study was to evaluate the effect of UV-C radiation on the sanitary state of fish meals. The research materials included salmon and cod meals. Samples of the fish meals were inoculated with suspensions of Salmonella, E. coli, enterococci, and C. sporogenes spores and exposed to the following surface UV-C fluencies: 0–400 J·m−2 for bacteria and 0–5000 J·m−2 for spores. For the vegetative forms, the highest theoretical lethal UV-C dose, ranging from 670.99 to 688.36 J·m−2 depending on the meal type, was determined for Salmonella. The lowest UV-C fluency of 363.34–363.95 J·m−2 was needed for the inactivation of Enterococcus spp. Spores were considerably more resistant, and the UV-C doses necessary for inactivation were 159571.1 J·m−2 in salmon meal and 66836.9 J·m−2 in cod meal. The application of UV-C radiation for the sanitization of fish meals proved to be a relatively effective method for vegetative forms of bacteria but was practically ineffective for spores.

Hygienic aspects of cattle slurry storage as tHe most popular and cHeapest metHod of Handling liquid animal excrements

Abstract Slurry is a very valuable natural fertilizer, but its improper use in agriculture poses a serious sanitary threat. Therefore its treatment before use for fertilization is advisable. One of such methods, which is still the most popular, is storage of liquid excrements. The aim of this study was to estimate the sanitization effectiveness of storage at 4ºC and 20ºC based on parameters describing the kinetics of changes in the population of some indicator bacteria in cattle slurry with different dry matter content. The material for the study was fresh cattle slurry. The liquid excrements used in the experiment had a dry matter content of 2, 6 and 14%. Slurry was stored at 4ºC and 20ºC. Bacilli of Salmonella Dublin, E. coli and enterococci were used as indicator bacteria. Number of microorganisms was determined based on MPN method in a 3-tube design. Basic parameters of the bacteria inactivation kinetics were calculated and statistical analysis was made using the program SAS 9.2 PL. In stored slurry a gradual elimination of all the studied microorganisms was observed. Hygienization effect of storage was smaller at 4ºC than at 20ºC and in excrements with a high dry matter content. Depending on storage temperature and dry matter proportion, the theoretical times of survival ranged from 81.85 to 220.80 days for bacilli of Salmonella Dublin, from 74.93 to 199.36 days for E. coli, and from 118.67 to 335.84 days for enterococci. The study showed explicitly that statutory time of slurry storage is insufficient to ensure its complete hygienization. Streszczenie Gnojowica stanowi bardzo wartościowy nawóz naturalny, jednak jej niewłaściwe zastosowanie w rolnictwie stwarza poważne zagrożenie sanitarno-higieniczne. W związku z powyższym celowa jest jej obróbka przed nawozowym wykorzystaniem. Jedną z metod, cieszącą się wciąż największą popularnością, jest składowanie płynnych odchodów. Celem badań była ocena skuteczności higienizacyjnej składowania w temperaturze 4 i 20ºC w oparciu o parametry opisujące kinetykę zmian populacji wybranych bakterii wskaźnikowych w gnojowicy bydlęcej o różnym udziale suchej masy. Materiał do badań stanowiła świeża gnojowica bydlęca. W badaniach wykorzystano płynne odchody o zawartości suchej masy: 2, 6 i 14%. Gnojowicę składowano w temperaturze 4 i 20ºC. Jako bakterie wskaźnikowe wykorzystano pałeczki Salmonella Dublin, E. coli oraz enterokoki. Liczbę drobnoustrojów ustalono w oparciu o metodę NPL w układzie 3-probówkowym. Obliczono podstawowe parametry kinetyki inaktywacji bakterii oraz przeprowadzono analizę statystyczną w programie SAS 9.2 PL. W składowanej gnojowicy obserwowano stopniową eliminację wszystkich badanych drobnoustrojów. Efekt higienizacyjny składowania był słabszy w temperaturze 4 niż 20ºC oraz w odchodach o wysokim udziale suchej masy. W zależności od temperatury składowania i udziału suchej masy teoretyczne czasy przeżycia wahały się dla pałeczek Salmonella Dublin od 81,85 do 220,80 dnia, dla E. coli - od 74,93 do 199,36 dnia, a dla enterokoków - od 118,67 do 335,84 dnia. Badania jednoznacznie wykazały, że ustawowo przewidziany czas składowania gnojowicy jest niewystarczający dla zapewnienia jej pełnej higienizacji.

Efficacy of radiant catalytic ionization to reduce bacterial populations in air and on different surfaces

Air contamination by biological agents is often observed in medical or veterinary facilities and industrial plants. Bioaerosols may sediment and pose the surface contamination. Microorganisms present on them may become a source of infections among humans and food contamination. This study determined the use of oxidative gases, including ozone and peroxide, generated by the Radiant Catalytic Ionization (RCI) cell for the inactivation of Acinetobacter baumannii, Escherichia coli, Enterococcus faecalis, Pseudomonas aeruginosa, Salmonella Enteritidis, Listeria monocytogenes, Staphylococcus aureus, Streptococcus epidermidis, Bacillus subtilis, Clostridium sporogenes, Candida albicans, Aspergillus niger and Penicillium chrysogenumon in air and on different surfaces. Results showed that oxidative gases produced by the RCI cell reduced all tested microorganisms. The full elimination of studied microorganisms from the air was obtained for E. coli and C. albicans. RCI also proved to be an effective method of eliminating microbes from the examined surfaces. Regarding of the species, strains origin and the type of surface, the reduction rate ranged from 19.0% for C. albicans to over 99% for A. baumanii. For both, air and surface, the most resistant to RCI was C. sporogenes spores, for which the percentage reduction rate ranged from -2.6% to 71.2% on the surfaces and was equal 71.7% in the air.

Proteus mirabilis biofilm - Qualitative and quantitative colorimetric methods-based evaluation

Proteus mirabilis strains ability to form biofilm is a current topic of a number of research worldwide. In this study the biofilm formation of P. mirabilis strains derived from urine of the catheterized and non-catheterized patients has been investigated. A total number of 39 P. mirabilis strains isolated from the urine samples of the patients of dr Antoni Jurasz University Hospital No. 1 in Bydgoszcz clinics between 2011 and 2012 was used. Biofilm formation was evaluated using two independent quantitative and qualitative methods with TTC (2,3,5-triphenyl-tetrazolium chloride) and CV (crystal violet) application. The obtained results confirmed biofilm formation by all the examined strains, except quantitative method with TTC, in which 7.7% of the strains did not have this ability. It was shown that P. mirabilis rods have the ability to form biofilm on the surfaces of both biomaterials applied, polystyrene and polyvinyl chloride (Nelaton catheters). The differences in ability to form biofilm observed between P. mirabilis strains derived from the urine of the catheterized and non-catheterized patients were not statistically significant.

Virulence genes and antimicrobial susceptibility of lactose-negative and lactose-positive strains of Escherichia coli isolated from pregnant women and neonates

Escherichia coli can cause serious infections in the neonates and pregnant women. Although E. coli is widely studied, E. coli lactose-negative (lac−) strains have been rarely described before. So, the aim of this study was to compare lac− and lactose-positive (lac+) E. coli strains in respect of antimicrobial susceptibility and the frequency of virulence genes (VGs). The study included 58 lac+ and 58 lac− E. coli strains isolated from pregnant women and neonates. Culture and the results of biochemical reactions were conducted for lac− and lac+ E. coli identification and differentiation. Disc diffusion test was performed to study the antimicrobial susceptibility of the isolates, and PCR was used to detect VGs. Resistance to at least one of the tested antibiotics was found among 14 (25.9%) E. coli lac+ and in 26 (44.9%) E. coli lac− strains. Both lac+ and lac− E. coli strains were mostly resistant to ampicillin (22.4 and 39.7%) and ticarcillin (20.7 and 39.7%). None of the tested strains produced extended-spectrum β-lactamases (ESBLs). Genes fimH, fimA, iutA, sfa/foc, neuC, ibeA, and hlyF were detected, respectively, in 96.6, 82.8, 32.8, 24.1, 22.4, 12.1, and 6.9% of lac+ E. coli strains and in 94.8, 86.2, 48.3, 19.0, 8.6, 8.6, and 1.7% of lac− strains. The antimicrobial susceptibility and the pathogenic potential of both tested groups of E. coli strains are similar. Therefore, omitting E. coli lac− strains as a potential etiological agent of infections may pose a threat to the health and life of both mothers and neonates.

The reduction rate of invasive Ascaris suum eggs number in slurry and humus layers of selected soil types

SummaryThe aim of this study was to determine under laboratory conditions the percentage and rate of reduction in invasive Ascaris suum eggs, as well as the maximal time of invasiveness retaining by them in swine slurry and 3 soil types. A. suum eggs were introduced into perforated perlon bags which then were placed in samples of slurry and in humus layers of the soils: podsolic soil, black earth and browned black earth. The experiment was carried out for 44 weeks at 4 and 20 °C. Finally, at 4 °C a reduction in the number of invasive eggs from 41 % (the humus layer of podsolic soil) to 65 % (the humus layer of black earth) was observed. At 20 °C the fluctuations were smaller and the percentage of elimination ranged from 89 % (slurry) to 96 % (the humus layer of browned black earth).

Effect of Microwave Radiation on Microorganisms in Fish Meals

Abstract This study was aimed at testing the effect of microwave radiation on survival of E. coli, Salmonella Enteritidis, Enterococcus spp. and Clostridium spores in two kinds of fish meals. The material used in the study consisted of samples of two kinds of fish meal – salmon and cod. In the experiment samples of both kinds of fish meals were inoculated with suspensions of tested bacteria and spores of Clostridum sporogenes. After inoculation the material was exposed to microwave radiation with a frequency of 2.45 ghz and microwave energy power of 0, 100, 180, 300, 450, 600 and 700 w, respectively, for 2.5 min for bacteria and 11 minutes for spores. then the reisolated microorganisms were counted and theoretical lethal doses of radiation were determined. among the studied vegetative forms of bacteria, the largest decreases in the numbers at the same radiation dose were observed in the rods of E. coli, whereas the smallest in enterococci. spores of Clostridium sporogenes showed a considerably higher resistance to the effect of that factor. the power of dose resulting in the complete inactivation of the studied bacteria should be about 430 kJ×g–1, and in the case of spores – 1 900 kJ×g–1.

Effect of storage temperature and type of slurry on survivability of Salmonella

The aim of this study was determination of the inactivation rate of Salmonella Senftenberg W775 and Salmonella Typhimurium in cattle and swine slurry stored under laboratory conditions at 4 and 20°C. Salmonella bacilli underwent constant, gradual elimination from the slurry during its storage. This process occurred more efficiently in samples stored at 20°C than at 4°C. At both studied temperatures elimination of bacteria was faster in swine slurry than in cattle. Shorter survivability in research material, in both temperature variants and kinds of slurry, showed Salmonella Typhimurium.

The impact of ethanol extract of propolis on biofilm forming by Proteus Mirabilis strains isolated from chronic wounds infections

Abstract Alcoholic propolis extracts may be used to eliminate microbes in mucous membranes and skin inflammations and in wound infections. The aim of this study was an assessment of the ethanol extract of propolis (EEP) activity against biofilm formation by P. mirabilis. Six clinical strains of P. mirabilis isolated from patients with chronic wound infection, and one reference strain of P. mirabilis ATCC 29906 were used. Biofilm was formed in 96-well plate. In order to evaluate the effect of EEP at a concentration range of 1.56–100 mg/mL on the forming and mature biofilm, P. mirabilis cells were released by sonication. In this study the effectiveness of 25–100 mg/mL of EEP on the forming P. mirabilis biofilm and concentrations of 25–50 mg/mL of EEP on formed biofilm has been demonstrated. Our results suggest the possibility of using the EEP in treatment of chronic wound infection caused by P. mirabilis.